Every year, Montréal is plunged into winter with the arrival of the first snowfall, experiencing typical monthly temperatures ranging from -6.3°C to -10.2°C, with frequent extremes as low as -25 °C in January and February. In addition, we have experienced wider ranges between the daily highs and lows during the last six years, with the highs often reaching the freezing point, which causes freeze-thaw cycles and the resulting formation of icicles in the tunnels.